Snakebites, responsible for more than 80,000 deaths annually, constitute one of the main current global health crises, especially in subtropical regions. Many venoms damage the tissue, leading to necrosis and hemorrhage at later stages. Studying these effects directly in animal models raises ethical concerns. However, replicating this damage in two-dimensional cell cultures is challenging. These two-dimensional cell cultures lack the vascular tubular morphology found in vivo. Without these structures, it is impossible to replicate the interactions that occur in the cellular microenvironment in vivo, such as blood flow and interaction with the extracellular environment. A study in Scientific Reports uses an organ-on-chip platform, creating a three-dimensional environment to grow human blood vessel models and simulate the hemorrhagic effect of different snake venoms while studying their direct toxicity to endothelial cells.

The team exposed the blood vessel models to the venom of four different common snakes. First, the team confirmed venom-induced leakage by observing whether the vessels injected with fluorescent dye leaked into the extracellular media. When checking for morphological damage, venom from Echis ocellatus significantly altered the general structure of the blood vessels, collapsing them at the higher dose of 10 µg/mL while creating localized gaps in the endothelial layer at 1 µg/mL. Venoms can produce a cytotoxic effect, whether by affecting the cells directly, disrupting the cellular membrane, or indirectly by affecting the extracellular matrix, which can eventually lead to cell injury. To study this cytotoxic effect, the researchers quantified the number of dead cells and changes at a cellular level. The findings show that venoms affect blood vessels in two main ways: delamination of the endothelial cell monolayer from its matrix and disruption of the endothelial cell membrane. By producing either cellular damage or structural damage, snake venoms produce vascular leakage, leading to localized or systemic hemorrhage, which can be replicated in this organ-on-a-chip system.

The workflow presented here can be used as a routine animal-free preliminary assessment of snake venom toxicity to study tissue-damaging and proteolytic effects, creating opportunities for the development of effective snakebite treatments.

Original reference: Bittenbinder, M.A. et al. Sci. Rep. 14, 11157 (2024)